The Role of Point Defects and Functionalizations in the Cyclic Voltammetry of Single-Walled Carbon Nanotubes

The use of carbon electrodes in electrochemistry is usually preceded by extensive surface functionalization or oxidative pretreatments to ``activate'' the carbon surface. Precise and quantitative determination of the role of this functionalization is exceedingly difficult. To understand the exact role of different surface groups, we utilize individual, single-walled carbon nanotubes (SWCNTs) as unique, nanoscale working electrodes. Cyclic voltammetry on pristine single SWCNTs quantitatively determines electron transfer rates for a perfect, defect-free graphitic surface of known area. Furthermore, the incorporation of single point defects in the SWCNT sidewall allows kinetic rates to be probed as a function of disorder. Cyclic voltammetry of the same SWCNT before and after the production of a point defect shows a pronounced enhancement of electrochemical activity that can be unambiguously ascribed to the presence of the functionalization. This research is partly supported by NSF (CBET-0729630) and a GAANN fellowship (VRK).